Alternating current operated noninterfering signaling system



Dec. 12; 1939. M. w. MUEHTER 2,183,245

ALTERNATING CURRENT OPERATED NONINTERFERING SIGNALING SYSTEM Original Filed July 13, 1934 lNV OR Ha rffred .l rekifr,

Patented 12, 1939 PATENT OFFICE ALTERNATING CURRENT OPERATED STON- INTERFERING SIGNALING SYSTEM ,Manl'red W. Muehter, Nutley, N. 1., assignor to American District Telegraph Company, Jersey City, N. J., a corporation of New Jersey.

Application July 13, 1934, Serial No. 734,931"

. Renewed April 26, 1939 21 Claims.

This invention relates to electric-signal systems and transmitters and receivers therefor, and more particularly to systems wherein a large number of transmitters on the same circuit are I prevented from interfering with each other,

though it is noted that in some of the claims the invention is not limited to systems of the non-interfering type.

One object of the invention is to provide an improved system of this kind in which the transmitters are provided with motors operated from the central source of current at the receiving station, and wherein the motor is operated by alternating current while intermittent direct current signal impulses are superposed on the alternating current.

Other objects of the invention are to provide, in a sy tem of this kind, improved signal means for indicating grounds and indicating line breaks and their removal.

Additional objects of the invention are to improve generally the simplicity and efliciency of such systems and apparatus and to provide an apparatus of this kind which are economical and reliable in operation, and economical to manufacture and install.

Still other objects of the invention will appear as the description proceeds; and while herein details of the invention are described in the specification and some of the claims, the invention is not limited to these, since many and various changes may be made without departing from the scope of the invention as claimed in the broader claims.

The inventive features for the accomplishment of these and other objects are shown herein in connection with a positive non-interfering suc- (essive signaling system. which briefly stated, includes a series of distant transmitters, each comprising an alternating current motor, and a coding switch operated by the motor.

The figure is a wiring diagram Showing the system.

The system may be used for sending code nals from distant stations as on subscribers premi es, and receiving them at a central or other office.

. The system shunt-switch l2 controlled by the cut-out cam. A double throw signal-initiating or detector switch l5 associated with each transmitter at or near the transmitter or at a distance therefrom, is used to initiate the signals. The detector switch has a movable element I6 which may be operated by hand, or which may be connected to a. valve, flow detector, thermometer or any hand or automatic device to be supervised, and moved I from normal position in engagement with a normally engaged contact II to engage a normally disengaged contact It. At the receiving or central station is located a coding relay'winding 2| adapted to pass direct current and substantially preventing passage of alternating current and a condenser 22 and choke coil 23, in series, shunting said winding to pass alternating current. At the receiving station is also a detector relay including a solenoid 26, an armature 21, a normally engaged contact 28 and a normally disengaged contact 29. There is also a transformer including a primary and a transformer secondary 36 in which is interposed a source 31 of directcurrent E. M. F. The main line circuit passes from. one end 38 of said secondary through conductor 39, the receiver coding winding 2|, or the condenser 22 and then as a detector loop 40 through each of said switches l2 and movable elements I6, to and through the break detector relay solenoid 26, said line circuit then continu- 30 ing as a motor loop 4i passing in the same direction as the detector loop through a terminal of each motor-field coil 42, to the other end 43 of said secondary, whereby current may pass and the detector relay winding is held energized and the line is supervised.

The transmitter A service line 45 in each transmitter is connected to the other end of the motor field coil 42 and through condenser 51 to the movable element of a change-over double throw switch having its fixed contacts 41, 48 connected to said detector switch contacts l1, I8 respectively. The movable element 46 of the change-over switch is controlled by the inner land portion 50 of said 45 change-over cam 9 to normally connect the service line with the normally disengaged detector switch contact l8 and before and during the first part of the code signal, and is controlled by the outer land portion 5| to connect the service line to the other fixed contact I! before and during the other part of the code signal. This permits the sending of a signalon the restoration to normal of the movable element l6, as will be explained.

The double throw shunt switch I2 in each transmitter is interposed in the detector loop adiacent to each detector, the elements 88, 88 normally maintain the continuity of loop 88 while the element 88 connected to the service line is operated by said cut-out cam 8 to separate elements 88, 88 and break the detector loop and connect the left leg only of the loop 88 with the service line through elements 88, 88, thereby to connect said service line with one end 88 of said secondary.

A condenser" is interposed in. said service line 85 adjacent to the motor, whereby when the detector element I8 engages contact I8 alternating current may pass to the motor, without passing direct current, thereby energizing the motor held and opening a normally closed cut-out switch 88, 58 in the motor loop, opened by the armature 88 attracted by the motor field when energized, to break motor loop 8I and leave the motor connected to the other end 83 only of said secondary, whereby all of the other transmitters are cut out and the break detector relay solenoid 28 is deenergized.

The condenser 22 and choke coil 23 in series around the coding solenoid allow alternating current to pass and the motor operates the transmitter and code wheel I8, intermittently closing a normally open code switch 82 shunting said condenser 51 and engaged by the code teeth I 2I to superpose direct current onthe alternating current, which direct current may pass the receiver coding solenoid 2I, as will be explained, and deliver code impulses to the'receiver winding, thereby attracting the armature 83, closing switch 83, 88, and passing direct current through conductors 88, 85 from one terminal, of the direct current source to the other to operate the recording register 81.

Normally, when the transmitter is not operat- "ing, the supervisory current does not pass through the coding winding 2|, but passes through a bypass 18 in which is interposed a normally closed switch H, 12 of a switching relay including a winding 13 and the normally closed by-pass switch 1|, 12, and ground switch 18, 15 and a normally open trouble switch 18, 11. Conductors 85, 18 connect one pole 88 of the direct current source with the armature 21 of the break detector relay; while conductors 8I, 82, 88 connect the normally disengaged contact 28 of said relay through the switching relay winding 18 to the other pole 83 of said source, whereby when the detector relay 28 is deenergized, the by-pass switch H, 12 is opened and the coding relay solenoid deshunted to cause the intermittent code signal current to pass through the winding 2| and actuate the register 81. The break indicating lamp 88 connected in parallel with the winding 13 lights whenever the solenoid 28 is deenergized.

The break detector A trouble-bell relay 85, 88, 81 is provided for operating a trouble bell 88 and comprises a winding 85, adapted when energized to close a circuit through terminal 88, conductors 85, 88', 88, contact 81, armature 88, conductors 88, 88 and terminal 83. A double throw silencing switch comprises a normally disengaged contact 88 con- 88, 81, 85 through said trouble switch 18, 11 to one pole 88 of said source 31, and a movable element 88 connected through conductor 88, resistor I88, conductor I8I, trouble winding 85 and conductors 88. 88 to the other pole 88 of said source, whereby when a break occurs anywhere in the mainline88,8l andtherelay 28isdeenergiaed, the relay winding" is energized, current pass through the trouble winding 88 and the bell 88 rings until the silencing switch movable element .88 is moved to the normally disengaged contact 88; and then when the break is mended and the break detector relay 28 energized and the switching relay winding 18 is deenergized. the trouble relay winding is energized through conductors 88, 88,188, "I, 88, 88 'and the trouble bell is again sounded until the silencing switch element 88 is moved to original position, thus breaking the circuit through winding 88.

The ground detector l The ground detector includes a ground detector relay comprising an armature I88 connected through conductors 18, 85 to the terminal 88 of said source 81, a normally engaged back contact I85, a normally disengaged front contact I88 and a solenoid I81 connected by conductors I88, III between the midpart of said source 31 and the element I 01 said ground switch, the other element 18 being grounded at the ground I I2, whereby when a ground occurs on the line 88, H the ground detector winding I81 is energized and the normally disengaged contact I88 thereof is engaged by the armature I88.

A double-pole ground-signal silencing-switch comprises a normally open switch H8, H5 and a double throw switch II 8, H1, H8, the latter switch having a normally engaged contact II8 connected by conductor .I8I to the trouble relay winding 85 and its movable element I I1 connected through conductors I 28, I2I, through a ground lamp I22 to the normally disengaged ground detector contact I88, whereby when there is' a ground and the contact I88 therefore engaged, the trouble bell is sounded until the double throw switch is thrown from contact II8 to contact II8, thus breaking the circuit through conductor I8I. The normally disengaged element I I8 is connected by conductors I23, 88 to the pole 83 of the source 31, whereby-the trouble lamp I22 continues to light, until the ground is repaired. The normally open switch H8, H5 is connected by conductors I25, 88 between the normally disengaged ground detector contact I88 and the trouble winding 85, and may, if desired, have its movable element I I8 mechanically connected by the insulating bar I28 to the movable element ill of the double-throw switch, whereby when the double throw switch is thrown to silence the ground bell, the trouble solenoid 85 is connected to the normally disengaged detector contact I88, thereby again to ring the bell when the ground is repaired, whereupon the silencing switch is thrown to normal and the lamp I22 and trouble solenoid 85 are deenergized.

It is noted that the lamp I22 lights whenever the winding I81 is energized because of ground; and that the lamp 88 lights whenever the solenoid 28 is deenergized by a line break. Thus, when the trouble bell sounds, these lamps indicate the kind oi. trouble.

. Normal operation The operation will be understood from the foregoing, and need now be only summarized as iol- 7o 1|; eesaive.

areas-1e I 3 In the diagram, the two loops It and ll are shown, which extend through the premises or territory from where signals are to be received. The normal supervisory circuit can be traced as lol- 6 lows: From battery terminal 80 through one-halt.

oi the secondary 36 of the transformer, through loop II in which switches Bl, B9 are connected in series, through the coil 26 oi relay 2!, through a loop 40, in which switches 58, 54 are connected 1!) in series, then through switch I I, I! o! the switch- 7 closing a circuit from loop ll through switch 40,-

80 l, condenser 51, motor I, to loop ll. Alternating current from the secondary windings It oi the transformer will fiow and start the motor. As the motor magnet becomes energized, the an:- iliary armature 60 of the switch I, I! will be t attracted, opening this switch. This shuts off the current for all transmitters and the loop ll of such switch, whereby winding ll is deenergized,

thus energizing relay winding ll through the back contact 29 of relay 2!. This energizing of O winding 13 opens the switch II, I! andinserts the coding relay winding 2| into loop 40. Thus the resistance oi the winding 26 is removed as the resistance oi'winding II is inserted, maintaining the resistance of the line more nearly constant.

The winding 2| is shunted by the by-pass consisting of the condenser 22 or condenser 22 in series with the choke coil "and t ed to allow free passage for the alternating c as the motor starts to'rotate, switch element II 7 A0 rides out of the notch I closing the switch I...

I and opening the switch OI, It thus shutting oil the current for all motors more remote irom ter- .minal 88. As was explained, the motors moreremote from terminal 0 were cut oil by switch ll,

45 ll. Other motors are thus prevented from running and-sending in-a signal at this time. The.

switch II, II when thus closed connects the line ll with the part of the loop to the left at element It, thus allowing the motor to continue to run in Q so case switch I, ll closes only momentarily.

As the code wheel it rotates, the coding switch 02 intermittently closes and shunts the con- .denser l'l according to the code to be transmitted. Every time this happens direct current will so fiow through loop ll, superimposing. itself on the alternating current. However, thedirect cur-, rent will fiow through the solenoid 2| instead of through'the by-pass 22, -23. This relay at- I tract the armature l3 and operate the register so a through its contact as. meihalf a re'voltb' tion of the code wheel shaft the first of the unlike code signals has been transmitted. Then the element II rides into the other notch i3. and the.

. switch 58, ll again closes. The outer land por- 65 tion ll of the cam I then also opens switch 40, ll

and closes switch ll, 41. Ii. element It has beenleft on contact ll, current is thus cut oil from the line ll and relay II is reenergized. Other motors can now send in a signal in a similar man- 10 new. Switch II, It has a lead in operation over switch It", so that iitwo or more transmitters are waiting to signal at the same time,"the

one nearest terminal 43 will always transmitbe' tore the others, thus making the operation suet. As soon If two switches i! operated at exactly the same time, the transmitter nearest terminal I will operate first. Suppose the lower transmitter to be operating; its switches 54 and 58 would be open and no current from 48 could pass open switch 58 of this transmitter, and therefore no current from terminal 48 could reach any other transmitter and no transmitter could operate. Suppose the upper right hand transmitter to be operating; its switches 54 and 58 would open: no current from 38, 39 could pass open switch 54 to reach and operate the other transmitters. Consider that themiddle transmitter is operating and that the switches ii of the two end transmitters are turned to start such end transmitters operating as soon as the middle transmitter .ceased operating and closed its switches 54 and 58. The instant these middle-transmitter switches closed, both end-transmitter switches I8. (being connected in multiple) would open or tend to open simultaneously immediately because they are operated by the motor field; but neither of the "switches" would open immediately, because it can open only after the cam 8 has made a considerable movement. .Thus switch I! has what is called a lead in operation over the switch ll. Thus both end-transmitter switches 58 would open or tend to open first (before switch 54) and when this took place, the switch 58 or the lower transmitter would open and prevent current from terminal 43 from passing to the other transmitters, and only the transmitter nearest 0 would operate. If for some reason switch 58 of the upper right end transmitter should open first, it

, would not prevent current 4! from reaching the 35 right end transmitter, whereupon 58 at lower end would open and cut off the upper transmitter from terminal ll before the upper end transmitter switch 54 could-open and cut off the lower end transmitter from terminal 38.,

If the element It remains on contact it, the second part of the code signal is not sent, but it the element It should be thrown back to its original position on contact IS, a new starting circuit will be established through the now closed switch 45 48, 41. Themotor will again start as before and send the second part of the signal in the same way as before, the coding being controlled by the second half I! of the code wheel, making the signal distinctive, from the one sent before from the half Ii, in order to indicate the position oi switch element It. After completing the second half of the revolution, all cams will be in normal position again as shown in the drawing.

Operation of the ground detector 66 attention 01' the operator to the ground condition.

The operator can silence the hell by throwing the I silencing switch elements Hi, I I1 to theleft, thus 70 breaking the circuit through coil by opening the switch H0, H1. The light, however, will not be extinguished until the ground trouble has been ,.removed, since current will then passthrough contact ill and conductors "3,".

ground is removed and the magnet I01 energized, when the switch elements H5, H1 are thus thrown to the left, the relay coil 85 will be energized through conductors 66, 98, the series re sistor I80, conductor 99, the right hand element H of the silencing switch, contact H4 and the back contact I05 of the ground relay. The bell will then ring again, when the ground is removed, and remind the operator to throw the silencing switch back to the normal position of the drawing.

A single ground on the line circuit 48, 4| will, however, not prevent the transmission of a regular .code signal, since relay coil 13, when energized during signaling as explained, opens its ground switch 14, 15, disconnecting the regular ground I I2 from the system. There will now only remain the trouble ground on the line, which willhave no effect.

Operation of the break detector If a break happens in the line 40, 4|, the break detecting relay 25 is deenergized, thus energizing switching relay coil 13 and the breakindicating lamp 84 in parallel therewith through,

the back contact 29. Trouble relay coil 85 is thus energized through its series resistor I88, conductor 99, switch 98, 95, conductor 96, relay switch 18, TI and conductors 91, 65. The trouble bell can be silenced by throwing the associated silencing switch element 98 to the left, while the break-indicating signal lamp 84 will remain lighted until the break has been cleared. When the break is cleared the relay 25 is energized causing current to pass through the trouble relay coil 85, the series resistor I08, the silencing switch 98, 93, and the contact 28 of relay 25, thus reminding the operator to throw the silencing switch element 98 back to its normal position shown in the drawing.

It will be noticed that a break in either of the two line wires will only prevent those transmitters from sending in a signal which are located on that side of the break where the supervisory relay 25 is connected. For instance, if the loop 48 be broken at some point between the detector switches l5, the part of this loop to the left of the break will be still connected to the terminal 38, and the transmitter 5 may operate as previously described. But the part of the loop 48 to the right of such break will not be connected to the terminal 38 at all, and the transmitter 6 cannot operate.

Whenever the bell 88 rings as a result of a break or a ground, the lamp 84 or I22 will indicate whether the defect is a break or a ground.

I claim as my invention:

1. In combination, a series of code impulse transmitters; a coding receiver; a break detector relay; a source of direct current; a main line passing as one loop from one pole of said source ad jacent to said transmitters and then through the detector relay winding, said line then continuing as a second loop in the same direction past said transmitters through the coding receiver to the other terminal of said source; a normally closed shunt shunting the coding receiver; means for connecting each transmitter between adjacent parts of the respective loops; means associated with each transmitter to break the loops respectively on respective opposite sides of such transmitter to leave only such transmitter connected in a circuit between opposite poles of said source thereby to deenergize the detector relay; and

means operated by the detector relay when deenergized to break said normally closed shunt.

2. In combination, a transmitter comprising an alternating current motor, and a coding switch operated by the motor; a coding receiver; a condenser shunting said receiver; a source of direct current; a conductor passing from one end of said source; to said condenser and thence to said transmitter; a second conductor passing from said transmitter to the other end of said source; means for connecting the coding switch and motor in series between the respective conductors; a condenser in the transmitter shunting the coding switch; and means to superpose alternating current F. on the direct current E. M. F.

3. In combination, a line; a condenser therein; a code switch shunting the condenser; and an alternating current motor in series with the coding switch operable by alternating current in the line for operating said switch.

4. In combination, a series of transmitters; a coding receiver; a resistance; a source of direct current; a main line passing as one loop from one terminal of said source through said transmitters and then through said resistance, and then continuing as a second loop through said transmitters to the other terminal of said source; means for connecting each transmitter between adjacent parts of the respective loops and removing said resistance from the line and simultaneously inserting said receiver.

5. In combination a pair of parallel lines, transmitters bridged therebetween and having code means adapted to make and break the bridge connection between said lines; and means operated by each transmitter for breaking one line at one side of each transmitter and the other line on the other side of such transmitter.

6. In combination, a series of code impulse transmitters; a coding receiver; a detector relay; a source of current including elements in series; a main line passing from one terminal of said source through said coding receiver, said transmitters and the detector relay winding to the other terminal of said source, to form a transmitting circuit and adapted to operate the detector relay during transmitting; a ground detector relay comprising a winding connected between a ground and the connection between said elements; to cause the ground relay when energized to energize the trouble alarm means; and

means operated by the detector relay during transmitting to remove said ground.

7. In combination, a pair of line loops; a series of transmitters, each transmitter including a service line connected between said loops; a motor in each transmitter started by current in the service line; a make and break code means, and a detector switch interposed in the service line; the motor operating the code means; the detector switch being operable to cause said current to start the motor; and means operated by the motor to break the loops on respectively one loop on one side of said line and the other loop on the other side of said line and to disconnect the motor service line from said detector switch.

8. In combination, a condenser; a code switch shunting the condenser; and a motor in series with the code swtch operable by pulsating current for operating the code switch.

9. In combination, a series of transmitters; a coding receiver; a D. C. source; a source of A. C. E. M. F. superposed on said D. C. source; a loop passing from one pole of said source adjacent to said transmitters; and a second loop passing said bridging means, a condenser shunting the code switch, and means operated by each motor, when its bridging means is connected.'to break the loops respectively each on the side 01 the bridging means most remote from the source to leave only one code switch connected to the receiver, and only the motor oi! such-switch connected to the'A. C. source.

'.10.'In combination, a series of transmitters;

a coding receiver; a source of current; a main line passing as one loop from one terminal or said source through said transmitters in bite direction and then continuing in said direction as a second loop through said transmitters and the receiver to the other terminal or said source; bridging means ineach transmitter adapted to be connected between adjacent parts of the respective loops; a

12. In combination, a series of code impulsetransmitters; a coding receiver; a detector relay;

v a source of current comprising elements connected in series; a main line passing as one loop adjacent to said transmitters and along the series in one direction from one pole of said source and then through the detector relay winding, said line then continuing as a second loop in the same direction past said series of transmitters through the coding receiver to the otherterminal of said source; means for. connecting each transmitter between adjacent parts of the respective loops during transmitting, thereby to short out and deenergize the detector relay winding; a ground detector connected to a part of said source between said elements and having a ground to conduct current when the line is grounded, to operate the ground detector; and means operated by thedetector relay when deenergized for removing said ground thereby to allow any operated transmitter to transmit to the receiver.

13. In combination, a series of code impulse transmitters; a coding receiver; a break detector relay; a source of current comprising elements connected in series; a mainline passing as one loop adjacent to said transmitters from one pole of said source and then through the detector relay winding, said line then continuing as a second loop in the same direction past said transmitters through the coding receiver to the other terminal of said source; bridging means tor connecting each transmitter between adjacent parts of the respective loops; means associated with each transmitter to break the loops respectively each at the side of such bridging means most remote from said source, thereby to deenergize the detector relay; a ground detector connected to said source between said elements and having a ground to conduct current when the line is grounded, to operate the ground detector; and

means operated by the break detector relay when I deenergized for removing said ground.

14. In combination, a line; a coding means in saidline operable to intermittently vary direct current'ln said line; pulsating motor means operable by pulsating current superposed in said line ioroperating said coding means; and means for allowing the pulsating current to pas the coding means while preventing the passage of direct current- '15. In combination, a line; a coding means in said line adapted to intermittently vary direct current in said line; a receiver operated by direct current in said line; an alternating current motor means in series with the coding means and operated'by alternating current in said line for operating said coding means; and a condenser shunting the coding means.

16. In combination, a line; a coding means in said line operable to intermittently vary direct current in said line; pulsating motor means operable by pulsating current superposed in said line for operating the coding means.-

17. In combination, ,a line; a coding means adapted to intermittently vary direct current inconnected to the mid part of said battery and having a groundtofconduct current when the line is grounded to operate the ground detector; a normally energized detector relay in said circuit; and means operated by the detector relay when deenergized to remove said ground detector from the circuit; said circuit comprising a line passing as one loop iromone terminal of the battery through said transmitters, then through the relay winding and as a second loop through said transmitters to the other terminal of the battery; a bridging means with a code switch therein in the associated transmitter adapted to be connected to adjacent parts of the respective loops during signalling; the arrangement of said circuit being such that a bridging means when connected cooperates with said circuit to bring about the function of shorting out said relay,'

thereby to remove the ground only while the bridging means is connected thereby to allow transmitting, when'a line is grounded, from any operatingtransmitter to the receiver. I

19. In combination, a circuit having a source of current; a ground detector interposed between the circuit and a ground; transmitters and a receiver so connected to the circuit that operation of any transmitter operates the receiver, during accidental grounding if said ground is removed; and means influenced by operation of a transmitter for removing said ground.

20. In combination, a circuit including therein a source including elements in series, and a receiver; a series of transmitters each having a means adapted to cause current variations in the receiver current when the transmitter operates; a ground detector connected to said circuitbetween said elements and having a ground to conduct current when the line is grounded to operate the ground detector; a detector relay in said circuit influenced to operate by circuit current change during transmitting; and means operatedby the detector relay when dee'nergized to remove said ground from the circuit,

21. In combination, a normally closed circuit including therein a receiver, and a source of current consisting 01' elements in series; a series of transmitters each having a coding means adapted to be connected in the circuit and to cause code current variations in the receiver current when the transmitter operates; a ground detector connected to said circuit between said elements and having a ground to conduct current when the line is grounded, thereby to operate the ground detector; a normally energized relay in said circuit; means operated by the relay when during transmitting.

MANFRED W. MUEH'I'ER. 

